My research is mainly aimed
at the high latitude oceans and, in particular, at their role
in climate and climate variability.

1.
Water Mass Transformation and the Overturning Circulation

Warm, salty waters of
subtropical origin flowing towards the high latitudes are
progressively cooled and transformed into the intermediate and
dense waters, which fill the bulk of the world ocean. Through
this transformation, the high latitudes contribute to driving
the oceans' circulation and their poleward heat transport.
Variations in the formation processes have been linked to both
past and modern climate variability as well as to model
predictions of future climate. My research has ranged from
investigating the details of the transformation process
itself, to the connection between the amount of dense water
formed, the poleward heat transport and the sinking (or
overturning) that is often associated with these regions. I
have primarily focused on the dense waters formed in the North
Atlantic's Labrador Sea and Nordic Seas and have integrated
both data analysis, simpled models as well as numerical
simulations.

2.
Export of Fresh Water from the Arctic region to the North
Atlantic

As part of our climate system,
the large amount of fresh water delivered to the Arctic region
by rivers and excess precipitation is transported out of the
Arctic by the ocean circulation. Variations in this pattern of
convergence/divergence have the potential to induce large
changes in ocean circulation and climate due to the strongly
stabilizing impact of fresh water on the ocean's
stratification. Therefore, it is important to map and monitor
the fresh water pathways between the Arctic and Subarctic
region and understand what physical mechanisms control their
variability. As a part of this effort, I have been measuring
the freshwater flow into the Labrador Sea through Hudson
Strait. Hudson Strait is also the main opening for the Hudson
Bay System: a large, inland Arctic sea whose ecosystem and
human settlements have been indicated as extremely vulnerable
to climate change.

3.
Ice-Sheet Ocean Interactions around Greenland

The Greenland Ice Sheet's
contribution to sea-level rise has doubled over the last
decade due to increased melting and, to a greater extent, to
the widespread acceleration of outlet glaciers around
Greenland. One of the mechanisms we believe may have triggered
this acceleration are changes in ocean circulation in the
North Atlantic which are delivering larger amounts of
subtropical waters to the high latitudes. If these waters
reach the glaciers, they will drive increased submarine
melting and change the force balance at the edge of the
glacier – resulting in glacier acceleration. To test
this hypothesis I have been collecting data at the edge of
several outlet glaciers in East Greenland. My goal is to map
the water property distribution and, more importantly,
understand the processes which control the heat transport (and
submarine melting) to the edge of Greenland's glaciers.

See the Projects section for a
more in depth discussion of the recent and current projects.